blyaaYaEbal

using System;
using System.IO;
using System.Linq;
using System.Windows.Forms;
using System.Runtime.Serialization.Formatters.Binary;
using System.Collections;
using System.Collections.Generic;

//namespace WindowsFormsApp5
{
    public partial class Form1 : Form
    {
        private Car[] _cars;
        private CarsData _carsData;
        private BinaryFormatter _binaryFormatter;
        private const string PATH = "CARS.dat";
        private Car _tempCar;

        public Form1()
        {
            InitializeComponent();
            _tempCar = new Car("","","","");
            _binaryFormatter = new BinaryFormatter();
            _cars = new Car[0];
            _carsData = new CarsData(_cars);
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            this.Text = DateTime.Now.ToString();

            if (File.Exists(PATH))
            {
                using (FileStream fileStream = new FileStream(PATH,FileMode.OpenOrCreate))
                {
                    _carsData = (CarsData)_binaryFormatter.Deserialize(fileStream);
                    _cars = _carsData._cars;

                    foreach (string color in _carsData._colors)
                        comboBox1.Items.Add(color);
                }
            }
            else
            {
                for (int i = 0; i < 6; i++)
                    comboBox1.Items.Add((Color)i);
            }
            ClearData();
        }

        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            textBox3.Text = comboBox1.Text;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            bool isFound = false;

            foreach (Car car in _cars)
            {
                if (car.StateNumber == _tempCar.StateNumber && car != _tempCar)
                {
                    isFound = true;
                }
            }

            if (isFound == false)
            {
                _tempCar.UpdateElements(textBox1.Text,textBox2.Text,textBox3.Text,textBox4.Text);
            }

            string[] _colors = new string[0];

            foreach (var item in comboBox1.Items)
                Add(ref _colors,item.ToString());
            _carsData.SetData(_cars, _colors);

            using (FileStream fileStream = new FileStream(PATH, FileMode.OpenOrCreate))
                _binaryFormatter.Serialize(fileStream,_carsData);
            groupBox1.Visible = false;
            ClearData();
        }

        private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
        {
            groupBox1.Visible = true;

            foreach (Car car in _cars)
            {
                if (car.StateNumber == comboBox2.SelectedItem.ToString())
                {
                    FillData(car);
                }
            }
        }

        private void FillData(Car car)
        {
            textBox1.Text = car.StateNumber;
            textBox2.Text = car.Model;
            textBox3.Text = car.Color;
            textBox4.Text = car.FullName;
        }

        private void button3_Click(object sender, EventArgs e)
        {
            foreach (Car car in _cars.ToArray())
                if (car.StateNumber.Contains(comboBox2.SelectedItem.ToString()))
                    RemoveCar(ref _cars, car);
            comboBox2.Items.Remove(comboBox2.SelectedItem);
        }

        private void RemoveCar(ref Car[] cars, Car car)
        {
            Car[] tempCars = new Car[cars.Length-1];

            for (int i = 0; i < cars.Length; i++)
                if (cars[i] != car)
                    tempCars[i] = cars[i];
            cars = tempCars;
        }

        private void button2_Click(object sender, EventArgs e)
        {
            ClearData();
        }

        private void ClearData()
        {
            textBox1.Text = "";
            textBox2.Text = "";
            textBox3.Text = "";
            textBox4.Text = "";
            comboBox2.Items.Clear();
            comboBox2.Text = "";
        }

        private void comboBox2_KeyPress(object sender, KeyPressEventArgs e)
        {
            bool isFound = false;

            if (e.KeyChar == (char) Keys.Enter)
            {
                comboBox2.Items.Clear();

                foreach (Car car in _cars.ToArray())
                {
                    if (car.StateNumber.Contains(comboBox2.Text))
                    {
                        isFound = true;
                        FillData(car);
                        comboBox2.Items.Add(car.StateNumber);
                    }
                }

                if (isFound == false)
                {
                    Add(ref _cars,new Car(comboBox2.Text,"","",""));
                    _tempCar = _cars[_cars.Length-1];
                    groupBox1.Visible = true;
                    FillData(_cars[_cars.Length-1]);
                }
            }
        }

        private void Add<T>(ref T[] array, T value)
        {
            T[] tempCars = new T[array.Length + 1];

            for (int i = 0; i < array.Length; i++)
                tempCars[i] = array[i];
            tempCars[tempCars.Length - 1] = value;
            array = tempCars;
        }

        private void textBox3_KeyPress(object sender, KeyPressEventArgs e)
        {
            bool isFound = false;

            if (e.KeyChar == (char)Keys.Enter)
            {
                foreach (string color in comboBox1.Items)
                {
                    if (textBox3.Text == color)
                    {
                        isFound = true;
                        comboBox1.SelectedItem = color;
                    }
                }

                if (isFound == false)
                {
                    comboBox1.Items.Add(textBox3.Text);
                    comboBox1.Text = comboBox1.Items[comboBox1.Items.Count-1].ToString();
                }
            }
        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            using (FileStream fileStream = new FileStream(PATH,FileMode.OpenOrCreate))
            {
                _binaryFormatter.Serialize(fileStream,_carsData);
            }
        }
    }

    public enum Color
    {
        неопределенный,
        белый,
        красный,
        фиолетовый,
        серый,
        зелёный
    }

    [Serializable]
    public class CarsData
    {
        public Car[] _cars;
        public string[] _colors;

        public CarsData(Car[] cars)
        {
            _colors = new string[0];
            _cars = cars;
        }

        public void SetData(Car[] cars, string[] colors)
        {
            _cars = cars;
            _colors = colors;
        }
    }

    [Serializable]
    public class Car
    {
        private string _stateNumber;
        private string _model;
        private string _color;
        private string _fullName;

        public string StateNumber => _stateNumber;
        public string Model => _model;
        public string Color => _color;
        public string FullName => _fullName;

        public Car(string stateNumber, string model, string color, string fullName)
        {
            _stateNumber = stateNumber;
            _model = model;
            _color = color;
            _fullName = fullName;
        }

        public void UpdateElements(string stateNumber, string model, string color, string fullName)
        {
            _stateNumber = stateNumber;
            _model = model;
            _color = color;
            _fullName = fullName;
        }
    }
}